This application claims benefit of Japanese Application No. 2000-273793 filed in Japan on Sep. 8, 2000, the contents of which are incorporated by this reference.
1. Field of the Invention
The present invention relates to an endoscope that is sterilized with high pressure steam after it is used.
2. Description of the Related Art
Conventionally, there are widely used medical endoscopes capable of observing internal organs and the like in a body cavity by inserting a slender insertion section into the body cavity and executing various types of treatment and remedy using a therapeutic device inserted into a therapeutic device channel when necessary.
Endoscopes used in a medical field observe internal organs and the like by inserting an insertion section into a body cavity and execute various types of treatment and remedy using a therapeutic device inserted into the therapeutic device channel of the endoscopes.
When a once-used endoscope and a therapeutic device are to be used for other patient again, they must be washed and sterilized after the completion of checkup and treatment to prevent infection through the endoscope and the therapeutic device among patients.
Recently, autoclave sterilization (high pressure steam sterilization) is mainly used to disinfect and sterilize medical equipment because the autoclave sterilization permits the medical equipment to be used just after sterilization and its running cost is less expensive.
For example, Japanese Unexamined Patent Application Publication No. 10-276968 discloses an endoscope to which an annealed tube is assembled so that sufficient sterilization can be executed repeatedly while preventing the shrink of a tube contained in the endoscope when the endoscope is subjected to autoclave sterilization.
However, in the endoscope described above, the amount of shrink of the annealed tube inserted into an insertion section is smaller than that of a flexible tube section that is mainly composed of an outer sheath layer of resin. As a result, there is a possibility that the tube is loosened in the insertion section. Thus, there is also a possibility of causing disadvantages in that the loosened tube presses and bends a light guide cable and other members contained in the endoscope.
In addition to the above, when the temperature of the endoscope is returned to an ordinary temperature after it is released from a thermal load generated in a high temperature/high pressure steam sterilization process, if the tube meanders in a loosened state, the inner surface of the tube may be scratched or the tube itself may be broken when a forceps, a brush, or the like is inserted into the tube because an amount of force necessary to insert is increased.
An object of the present invention is to provide an endoscope which is unlikely to cause disadvantages in workability and handling by reducing looseness caused to a tube to be inserted into an insertion section when the endoscope is subjected to a thermal load in a high temperature/high pressure steam sterilization process.
Briefly, an endoscope of the present invention includes a flexible tube section having an outer sheath layer composed of resin for constituting an endoscope insertion section and a slender tube member inserted into the endoscope insertion section, wherein the amount of shrink of the tube member after the completion of a high temperature/high pressure steam sterilization process is set as much as or greater than the amount of shrink of the flexible tube section after the completion of the high temperature/high pressure steam sterilization process. Accordingly, when a thermal load is applied to the endoscope in the high temperature/high pressure steam sterilization process, it can be prevented that the tube member loosens and meanders in the flexible tube section and damages contained members by pressing them.